1.    30 Jan 2016 #1
    Join Date : Jan 2016
    Sri Lanka
    Posts : 2
    Windows 10

    Missing Operating System - Win10 Won't/Virtual Install

    Hi guys - I've browsed the forums for solutions but thought I'd ask here anyway:

    Summary: I'm trying to install Windows 10 on my HP G4 Pavillion laptop and I'm encountering a Missing Operating System loop after a seemingly successful first phase install.


    1. My Hp laptop came with Win7 Home PreInstalled
    2. Two months ago I upgraded to Win10
    3. Last week my harddrive failed although I managed to recover some data
    4. I purchased a new 1TB harddrive and mounted it on my Desktop PC using a USB harrdrive dock. This desktop runs Win8.1. Like a smart alec I created 3 partitions - 1 for the new Windows to come, 1 for the old laptop data & one for all my dropbox files.
    5. I installed this drive into the laptop.
    6. I attempted to install Win10 via USB
    7. I'm greeted with a window that displays the 3 partitions (Where Do you Want to Install Windows).
    8. After receiving a few errors (in haste I did not record these - I recall the term GPT) I formatted and deleted these partitions to create one singular unallocated harddrive
    9. I tried reinstalling Win10 via the USB
    10. I got to the same window and selected this drive
    11. Windows 10 finalised the install process and notified me that the laptop would reboot
    12. After the ''Press Esc key for Startup Menu'' I am greeted with a ''Missing Operating System'' message
    13. I restart & select USB drive to install windows again
    14. I'm greeted with the same screens as previously
    15. The Window showing the harrdrives and partitions however, now shows the following:

    Drive 0 Partition 1: Recovery Total Size: 450mb Freespace 147.0 MB Type: Recovery
    Drive 0 Partition 2: Total Size: 100MB Freespace 76MB Type: System
    Drive 0 Partition 3 Total Size: 16MB FreeSpace 16MB Type MSR (Reserved)
    Drive 0 Partition 4 Total Size: 931 GB Free Space 914GB Type Primary

    16. Naturally I select Drive 0 Partition 4 (Primary) and click Next
    17. Windows Installs as previously and reboots
    18. I am met with the same Operating System Missing message.
    19 I have tried a Repair Install instead of the Install feature but was greeted with the 'There was a problem resetting windows'
    20. I did try certain bootrec commands and sadly in haste didn't record the results - all the operations completed successfully but it appears Windows has not installed to this disc. (I forget which command informed me of this but No OS partition was found.
    21. I have tried formatting and deleting the above 1-4 partitions to make 1 ''original'' unallocated disc but am greeted with the same state.

    Item: I've tried updating the BIOS but HPs instructions on the subject do not seem to work. (Basically I havent found a way to a) create a Bios recovery USB nor have I found a method to upgrade using the existing bios.) The BIOS is Insyde F.25 version. I was previously able to upgrade the machine to Win10 via MS Upgrade within windows.
    Item: When I remove the USB drive or CD I'm greeted with a ''No Bootable Device - insert boot disk and press any key'' message
    Item: If I select Notebook Harddisk from the boot menu I am greeted with the Missing OS message as usual.
    Item: I have tried both with Product Key and I dont have a Product Key Options (I have a printed sticker for Win7)
    Iitem: Knoppix works - I'm wondering if I should try formatting the HD through that

    The only way to progress is to install Win10 from the USB or DVD all over again, format the partitions and watch it install only to get stuck in an endless loop. It's almost as if the installation is running virtually and no files are actually being copied!

    Any help would be much, much appreciated as I don't have time to order HP recovery discs and need to use the laptop for a presentation on Monday. Thank you very much and I'm ready to supply any further info.
      My System SpecsSystem Spec

  2.    30 Jan 2016 #2
    Join Date : Dec 2015
    Posts : 2,154

    It sounds to me like your pc is trying to boot in legacy bios mode, but install is eufi based. I am guessing original Windows 7 wass installed in legacy bios mode.

    Check your bios settings - there is often a switch to change to eufi mode.

    If there is no switch, you could download Windows 10 iso, create a usb stick using rufus, and make an installation suitable for mbr based partitions ie a legacy biosd install instead.
      My System SpecsSystem Spec

  3.    30 Jan 2016 #3

    Hi there.

    I think your original problem is that you were trying to INSTALL windows on a USB drive so you've have problems as Windows (unless it's Windows to Go) will NOT boot from a USB device.

    You can of course Boot from a USB drive to INSTALL Windows..

    So I'd start again -- do the following

    1) Insert the HDD into your laptop
    2) ensure you have a bootable USB Windows install USB stick -- you can make one from the Ms site.
    3) Install W10

    Should boot from the HDD now. Windows should format the HDD etc.

    If the HDD is hosed up enter RECOVERY MODE

    Use ADMIN mode with Dos prompt (sorry Cmd mode --must be showing my age !!!).

    2) LIST DISK
    3) SELECT DISK nn where nn is the nr of your HDD
    4) CLEAN
    7) ACTIVE
    8) EXIT

    Now have another go at W10 install.

    As it's a laptop and a 1TB drive you can leave it as MBR even with a UEFI computer - Windows install will take care of it. Leave UEFI on but don't use Secure Boot.

    I'd still at Windows install time say create a 70GB partition for Windows and use the rest for Data etc --it's a lot easier if you backup / restore windows again and you won't lose any data. Set up partitions when the Windows install prompt comes up showing the HDD.

    If for some strange reason your computer doesn't like MBR on UEFI mode BIOS then get back into Windows recovery mode and use admin CMD Prompt :

    2) LIST DISK
    3) SELECT DISK nn where nn is the HDD nr
    5) EXIT.

    Now insert USB drive and re-install again.

      My System SpecsSystem Spec

  4.    31 Jan 2016 #4
    Join Date : Jan 2016
    Sri Lanka
    Posts : 2
    Windows 10

    Thank you so very much for your swift and succinct replies - I used Rufus to prepare the USB and everything went ahead like a charm. I didn't need to use any recovery or cmd features either.

    Thanks again!
      My System SpecsSystem Spec


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